I would suggest that haproxy (which has a commercial version and appliance) are more of a competitor to F5. NGinx is first and foremost a web server with excel

I would suggest that haproxy (which has a commercial version and appliance) are more of a competitor to F5. NGinx is first and foremost a web server with excellent controls around caching. Haproxy is a load balancer with some caching as of version 1.9. F5 has always provided a web server in their load balancer via apache, but that is for management of the device itself. It can also serve up static web pages (primarily meant for error and landing pages).